Hemicellulose Removal in Curaua (Ananas erectifolius) Fibers for Polyester Composites

Introduction: Alkaline treatments extract hemicellulose from the fibers, which can be reused in the manufacture of other materials, and the cellulosic portion can be applied as reinforcement in a composite. This way, all components of the fibers are utilized. Method: In this work, curaua fibers (Ananas erectifolius) were treated with potassium hydroxide (KOH) to solubilize part of the hemicellulose and lignin, and the cellulose-rich fibers were used to manufacture composites with unsaturated polyester, which were characterized to investigate the effect of the treatment on their properties. Results: The alkaline treatment removed large portions of hemicellulose and significantly degraded the crystalline cellulose and lignin, resulting in a small increase (2.4%) in overall crystallinity and with a negative impact on their thermal stability. SEM images showed defibrillation of the treated fiber and fibril separation, increasing roughness and surface contact area. Conclusions: In all, although the alkaline treatment substantially modified the fibers and no significant changes were observed in the mechanical properties of the composite, the total removal of hemicellulose was found to affect the integrity of cellulose fibers making harder their application as reinforcement. However, the higher cellulose content could be useful for other applications